Current and future public health is characterized by the increase of chronic and degenerative diseases, corresponding to the worldwide ageing of the population. The increasing prevalence of these conditions together with the long incubation period of the chronic diseases and the continual technological innovations, offer new opportunities to develop strategies for early diagnosis.
Public Health has an important mandate to critically assess the promises and the pitfalls of disease screening strategies. This MOOC will help you understand important concepts for screening programs that will be explored through a series of examples that are the most relevant to public health today. We will conclude with expert interviews that explore future topics that will be important for screening.
By the end of this MOOC, students should have the competency needed to be involved in the scientific field of screening, and understand the public health perspective in screening programs.
This MOOC has been designed by the University of Geneva and the University of Lausanne.
This MOOC has been prepared under the auspices of the Ecole romande de santé publique (www.ersp.ch) by Prof. Fred Paccaud, MD, MSc, Head of the Institute of Social and Preventive Medicine in Lausanne (www.iumsp.ch), in collaboration with Professor Antoine Flahault, MD, PhD, head of the Institute of Global Health, Geneva (https://www.unige.ch/medecine/isg/en/) and Prof. Gillian Bartlett-Esquilant (McGill University, Quebec/ Institute of Social and Preventive Medicine, Lausanne).

From the lesson

Introduction to Key Concepts in Screening

This module will provide a brief welcome by Dr. Fred Paccaud and Dr. Antoine Flahault. An overview of screening and an introduction on how the course is organized and evaluated will be provided by Dr. Gillian Bartlett-Esquilant. Dr. Idris Guessous, a Senior Lecturer in the Population Epidemiology Unit in the Department of Community Medicine, Primary Care and Emergency Medicine (Geneva), and in the Department of Ambulatory Care and Community Medicine (PMU Lausanne) & Division of Chronic Diseases at the Institute of Social and Preventive Medicine (Lausanne) will provide lectures on definitions of screening. Natural history of diseases and the characteristics of subclinical conditions allowing early diagnosis will be presented. A quiz on the key concepts for screening will complete this module.

Meet the Instructors

Antoine Flahault

Professor of Public Health and Director of the Institute of Global Health (Faculty of Medicine, University of Geneva) and co-Director of Centre Virchow-Villermé (Université Paris Descartes)University of Geneva and Université Paris Descartes – Sorbonne Paris Cité

Fred Paccaud (In Partnership with UNIGE)

Professor of epidemiology and public health and Director of the Institute of social and preventive medicineLausanne University Hospital

Gillian Bartlett-Esquilant

Professor of Epidemiology and Research and Graduate Program Director and Associate Chair for the Department of Family Medicine at McGill University.University of Lausannne and McGill University

So, as said, we will not discuss the bias specifically in this module.

This will be discussed in other modules,

but here's an exception,

I would say. Just by relating the lead time we have discussed,

the time that the diagnosis and treatment is

made or are made earlier than usual practice,

how is this lead time related to overdiagnoses?

And there is something really fundamental to understand is that we

describe overdiagnoses as a disease that has been diagnosed, but the individual,

If you had not diagnosed the disease,

not even treated the disease,

the individual would have no impact on his or her health.

So, basically, you overdiagnosed an individual or a population.

And overdiagnosis here can be defined as

an indefinitely long lead time because the disease,

as I said, would never come to medical attention without screening.

And if you understand the concept of lead time in this module,

it will be really easier for you to capture,

to master the different bias encountered in screening, notably overdiagnosis.

We will talk about prevention and natural history of disease.

In this lesson, we will specifically discuss secondary primary prevention,

as well as, what we call, primordial prevention.

As you can see on the slide,

you have, again, the natural history of disease with the risk factors,

the preclinical stage, the signs symptoms,

and the consequence of the disease.

To understand prevention, you have to know how prevention fits.

Here, it's clinical care.

Once you have the disease, the symptoms,

you have a clinical care or our usual clinical care.

Secondary prevention is here.

The disease has started.

You are trying to prevent the evolution of the disease so that

you ameliorate or you

improve the prognostic of the disease but the disease has already started.

This is not the case in what we call primary prevention.

You want to avoid the disease to start by making someone stop smoking.

You want to avoid a new case of lung cancer.

Screening again is not about avoiding the disease,

it's about mitigating the impact of the disease.

And you can even do something more,

what we call primordial prevention or even health promotion by law.

You can say, this place,

there's no place for smokers.

You would ban smoking in your country, in your county,

and, basically, you would not even have to make the people stop smoking,

stop drinking too much because there will be no cigarettes,

there will be no alcohol, et cetera.

This is what we call primordial prevention.

Again, screening, what we call secondary prevention,

is about improving the prognostic of the disease.

And there is no point to screen a disease if there is no improvement of the outcome.